1Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-8555, Japan, 2Department of Biology, Tianjin Normal University, Hexi, Tianjin 300074, China
To evaluate the genetic variability of the silver carp Hypophthalmichthys molitrix population in the Tone River (Japan), which was introduced from the Yangtze River (China), the first half of the mtDNA control region was sequenced for 56 individuals including the adults, eggs and larvae. The results showed that the number of haplotypes (A) was 26, haplotype diversity (h) was 0.920, and nucleotide diversity (π) was 0.011. Phylogenetic relationships among haplotypes showed that the Tone River population possesses closely related haplotypes that were also detected in populations of the middle and lower Yangtze (published data), suggesting that the Tone River population originated from the middle and lower Yangtze. The high genetic variability, which is almost equivalent to that of wild populations, suggests that the Tone River population has been maintained by a considerable effective number of population (Ne) since being introduced.